Agreed.
You chose a budgie, now respect that relationship and make it work. Its like saying to your partner/spouse 'oh sorry, I found someone flashier and younger than you who's more exciting---see ya!'
Sure the new and flashy seems like 'all you ever wanted' and makes your budgie 'seem like a turnip' but pause and think a minute---what are the downsides to a sun conure and the upsides to a budgie you aren't seeing now due to infatuation?
That sun might be more interactive and flashy---but they're loud as hell, nippy and hyperactive.
Your budgie might be a little less hands on---but I bet he's quiet, cheerful and non-intrusive right?
It's a dangerous head-space to get into--acquiring more and more birds to try and fill the dream 'of the ideal bird'---and you end up with a house full of under-stimulated and stressed out birds because you kept getting one more to try and have the relationship with it that you didn't get with the last one, or your dreams that it didn't fulfill . I've been there. Don't do it. The cockatiel was supposed to a quieter, cuddly bird that didn't pluck, the linnie was to be a pocket parrot that would be my buddy who went everywhere with me...in the end the tiel was spooky and screamed, the linnie bit and didn't like hands...and my grey plucked more and was upset with all the other birds.
Don't just think of the conure in the context of the bird in the store, think of it in the context of your life and routine, plus with the bird you already have. Can you afford the same amount of time to Fleury plus give the conure fair attention time too? Can you afford double the expenses, vet bills, cleaning times...?
What happens when the conure hates Fleury or tries to kill him? Who becomes the 'other' bird who gets locked in the cage while the other one gets most of your time and attention? Who gets to go along for outings? If the answer would be the conure I think you've done your budgie a great disrespect and disservice and tossed him aside like an old toy---he was here first and you should love and respect your relationship.
Jacko will probably never talk like Alex or Einstein, or be colourful like a macaw, she'll never trill and chatter like an amazon or dance and solve puzzles like a cockatoo---but she is sweet, knows me more than anyone, calms me, loves to be scritched, and is a quiet, goofy bird who bites rarely and travels well. I love her and am so happy at how much of an awesome bird she is, focusing on the blessings she brings instead of what she does not.
